Rock Gardens

An open, south or southwest facing slope with plenty of sun is an ideal site for a rock garden.

When planting a rock garden be sure to amend your soil to ensure good drainage. A good blend is 1/3 compost, 1/3 native soil, and 1/3 pumice added to create a loose, well draining mix.

For the first year deep watering is essential, especially on hot days. The second year water only when temperatures are above 75 degrees. The third year there should be no need to water because plants should have a well established, deep root system which will help them be drought tolerant.

If your design includes mounds or hilling be aware that these areas will dry out faster.

Most rock garden plants don’t need fertilizer. Over the years the best thing to do is to refresh the soil around the plants with a top dressing of compost.

The most successful gardens are those where the plants grown are naturally suited or adaptable to the conditions of the soil, situation, and climate. Native plants are an excellent place to start.

If you pick mostly evergreen, drought tolerant plants you will have little or no maintenance except weeding. Covering the soil with 1-2” of gravel or crushed stone will reduce weeding dramatically.

Here’s a short list of plants to get you started:

Acaena - fast growing, dense evergreen ground cover. ☼ ☀
Ajuga - ground cover with blue flower spikes in the spring, deer resistant.☼ ☀ ☁
Aquilegia flabella & alpina - variety of two tone flowers that bloom spring through summer. ☼ ☀
Aster alpinus - forms a compact mound that blooms white flowers, in May and June. ☼ ☀
Aubrieta - vigorous, mat forming ground cover, flowers in early spring. ☼ ☀
Aurinia - clusters of gold flowers in spring, evergreen. ☼ ☀
Bellis perennis - daisy-like flowers in red, pink, or white. ☼ ☀
Campanula carpatica - blue or white bell shaped flowers through early summer. ☼ ☀
Daphne ‘Lawrence Crocker’ - evergreen, purple flowers spring to fall. ☼ ☀
Delosperma - evergreen succulent, ground cover, flowers late spring to summer. ☼
Dianthus - mid-summer blooms in various colors, deer resistant. ☼
Erigeron - clump forming, daisy-like flowers from spring to summer. ☼ ☀
Erodium - low growing compact plant which flowers April – October. ☼
Festuca - durable clumping mounds of blue, spiky foliage. ☼
Gentiana acaulis & others - mat of glossy leaves with blue trumpet flowers in summer. ☼
Geum - evergreen with tall, brightly colored flowers. ☼ ☀
Gypsophila repens - abundant clusters of pink or white flowers from spring into summer. ☼
Herniaria - tiny, bright green, trailing foliage that turns reddish in the fall. ☼ ☀
Iberis - mounding or trailing with white flowers in spring. ☼
Lewisia - semi-succulent plants, bloom white to pink or gold from spring to early summer. ☼ ☀
Lithodora - evergreen, trailing ground cover with blue, star-shaped flowers in early spring. ☼
Papaver alpinum & nudicaule - readily reseeds white, yellow or peach flowers in midsummer. ☼
Parahebe catarractae - summer blooming, small saucer-shaped flowers with pointed petals. ☼
Potentilla - spreading, clumping, evergreen with clusters of flowers in early summer. ☼
Pulsatilla - bell or cup-shaped flowers in late spring mature to feathery seed heads. ☼
Saxifraga - cushion forming evergreen with small flowers in spring. ☼ ☀
Sedum - there are many types of these succulents from short ground cover to upright. ☼
Scleranthus - low growing green mat. ☼ ☀
Sempervivum - Great low growing succulent for rock walls, needs little soil. ☼
Thymus - mounding, spreading habit with aromatic leaves and small flowers. ☼ ☀
Veronica repens - ground cover with small blue or white star-shaped flowers. ☼ ☀

Key to symbols:
☼ = Full sun; ☀ = Partial shade; ☁ = Full shade

Planting Suggestions

Rock gardens by design imitate native land- scapes that grow in natural stone outcroppings, such as those found in an alpine meadow. Contemporary rock gardens are less strict about plant selection, being more a matter of using rocks, plants, and boulders in a naturalistic garden style.

This is also known as a rockery. Rock gardens mostly include low growing perennials or shrubs with a mounding habit. These plants effectively resist wind and snow at high elevation. But there is great diversity in rock garden plants, not only as regards to shape, but also bloom time and color. Many alpine or high altitude plants will do well in a rockery.

A rock garden can be ideal for Northwest gardeners who don’t have a lot of time. Once the rock garden is established there is little or no maintenance except some light weeding. They also can be as big or as small as you want. If garden space is not available, rock gardens can also be made in pots or troughs. The plants which can be grown in a rock garden are almost innumerable.